If an unconstrained steel bar is heated uniformly, there develops

19) Which mechanism produces mathematically exact straight line motion?

20) An electron has a constant acceleration of + 3.2 m/square seconds. At a certain instant velocity is +9.6 m/s. The velocity of the electron 2.5 s earlier was.

21) A rotating fan completes 1200 revolutions every minute. If the tip of the blade is at a radius of 0.7 m, then the blade tip speed is (take Pie=22/7)

22) A can has a total volume of 1200 cubic centimeter and a mass of 200 g. How many grams of lead shots of density 11.4 g/cubic centimeter could it carry without sinking in water? (density of water : 1 g/cubic centimeter)